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Tuesday, October 17, 2000



Star found pushing
through the heart
of our galaxy

The Mauna Kea finding could
alter how astronomers understand
the center of the Milky Way, which
is called 'a beehive of activity'


By Rod Thompson
Star-Bulletin

A star plowing through a field of gas at the heart of the Milky Way galaxy, creating a bow-shaped shock wave in front of it, is part of a first glimpse into the universe from the new Gemini North observatory atop Mauna Kea.

"This finding could alter our understanding of the center of our galaxy once astronomers determine how the star and gas cloud are moving relative to each other," observatory spokesman Peter Michaud said.

The observatory was dedicated June 25, 1999, and its first scientific observations in July and August involved a look at the center of the Milky Way, which a Gemini press release described as "a beehive of activity with hapless stars flung around the core at tremendous speeds" in the center of the galaxy.

"There has been a buzz of increased interest by astronomers lately in looking at the properties of the core," said astronomer Andrea Ghez from the University of California-Los Angeles, whose work with the W.M. Keck Observatory last month calculated the location of a black hole in the center of the galaxy.

Ghez joined the Gemini team headed by Francois Rigaut, which continued studying the area around the black hole and discovered the star designated IRS8 pushing through a gas cloud.

Astronomers had known something was happening there. But images from other instruments had shown an "ill-defined smudge," Michaud said.

The Gemini team used a device built at the University of Hawaii Institute for Astronomy called Hokupaa (fixed star), which takes the twinkle out of stars. The device analyzes how Earth's atmosphere makes a reference star twinkle, then smooths out the twinkle.

"Never before have we seen such a large area of the galactic center this clear," Rigaut said.

IRS8 is moving through a poorly understood gas cloud about three light years from the black hole, Michaud said.

"By studying this interaction, the properties of the gas cloud and the conditions surrounding the star will be better understood and provide a valuable tool for probing the intense conditions near the center of our galaxy."

IRS8 is one of numerous stars that provide data in the Gemini image. "In the next four to five months we can expect a lot of scientific papers," Michaud said.

"This is the first science. It's a lot more difficult to get scientific data than a pretty picture."


Images of IRS8



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